Question: What do the following two equations represent? $-x-y = 3$ $5x-5y = 3$
Solution: Putting the first equation in $y = mx + b$ form gives: $-x-y = 3$ $-y = x+3$ $y = -1x - 3$ Putting the second equation in $y = mx + b$ form gives: $5x-5y = 3$ $-5y = -5x+3$ $y = 1x - \dfrac{3}{5}$ The slopes are negative inverses of each other, so the lines are perpendicular.